This invention relates to the melt reduction of iron oxides. U.S. Pat. No. 3,940,551, dated Feb. 24, 1976, and U.S. patent application Ser. No. 588,179, filed June 19, 1975, disclose melt reduction practices wherein, using a DC arc furnace, iron oxide material, such as iron ore, and carbonaceous material, in the form of mixed particles, are fed as directly as possible into an arc formed between a cathodic arcing electrode and an anodic carbonaceous iron melt. In both cases the arcing electrode is made with a longitudinally extending passage through which the materials are fed into the arc formed by the electrode. The direct current arc forms a spot on the iron melt where the slag is displaced to expose bare iron so that the desired reaction between the iron oxides and carbon of the two materials can proceed with maximum rapidity.
The arcing electrode is stationary in the horizontal direction, so the feed of the materials through the electrode is correspondingly stationary in that direction. Therefore, it would seem that the feed of the materials should go directly to the bare spot formed on the melt by the action of the arc.
Unfortunately, it has been found that the arc and, therefore, the spot wanders around in a random fashion in the horizontal direction, this, in turn, meaning that the feed of the materials is sometimes into the bare iron spot and sometimes into slag floating on the melt, because the arc action cannot immediately displace the slag as the arc wanders. This makes the reaction rate between the iron oxides and the carbon an unpredictable variable and not the maximum possible rate desired.
Although not relating to the melt reduction of iron, U.S. Pat. No. 3,789,127, dated Jan. 29, 1974 and U.S. Pat. No. 3,835,230, dated Sept. 10, 1974, disclose that when at least three DC arcing electrodes operating as cathodes, are symmetrically positioned about a common vertical axis above a melt which operates as an anode, the arcs formed between the electrodes and the melt, converge towards the common axis.